Various methods may be used for the selection and identification of compounds capable of binding specifically to a target in the presence of undesired background targets (anti-targets) using libraries of similar compounds. This invention is directed to peptides that bind specifically to a target such as skin or hair in the presence of an anti-target. The anti-target is hair when the target is skin and the anti-target is skin when the target is hair.
The literature is replete with examples of recent advances in methods for screening large library pools of compounds, especially peptides. Methods for screening these compounds to identify molecules that bind to a preselected target have also been advanced. One well-known method is biopanning which was originally developed by Smith, G. P., (1985), Science 228:1315. Biopanning in its simplest form is an in vitro selection process in which a library of phage-displayed peptides is incubated with a target. The target and phage are allowed to bind and unbound phage are washed away. The specifically bound phage are then acid eluted. The eluted pool of phage is amplified in vivo and the process is repeated. After a number of rounds individual clones are isolated and sequenced.
A number of variations of the biopanning technique first introduced by Smith have been described, and reference is made to Christian et al., (1992) J. Mol. Biol., 227:711; Cwirla et al., (1990) Proc. Natl. Acad. Sci. USA, 87:6378; Cull et al., (1992) Proc. Natl. Acad. Sci. USA, 89:1865; Huls et al., (1996) Nature Biotechnol., 7:276; and Bartoli et al., (1998) Nature Biotechnol., 16:1068.
Huls et al., 1996 supra, describe a method comprising flow cytometry-based subtractive selection of phage antibody on intact tumor cells. The phage-displayed antibodies remain bound to the target during the flow-cytometric selection. However, prior to amplification the cell-bound phages are eluted from the target. WO 98/54312 discloses selection of antibodies under mild conditions with high affinities for antigens using antibody libraries displayed on ribosomes.
Balass et al., (1996) Anal. Biochem., 243:264, describe the selection of high-affinity phage-peptides from phage-peptide libraries using a biotinylated target immobilized on a nitrostreptavidin matrix. Other targeting methods include, for example, SELEX (U.S. Pat. No. 5,475,096) and selective targeting which includes deselection as disclosed in WO 01/79479.